Mertesacker, 29, joined the Gunners from Werder Bremen in summer 2011. He played 21 times in the Premier League in his first campaign but suffered an injury towards the end of the season and lost his place in the Germany XI for the 2012 European Championships.

He went on to make 33 league appearances in the following season, and was a key component of last season's Arsenal side as they won the FA Cup -- manager Arsene Wenger's first trophy for nine years.

"It was certainly my best year since my transfer to Arsenal," Mertesacker told kicker. "I had a difficult first year, and the second one was a transition year. I have now arrived in England -- I have definitely worked out something."

"I did not have a single injury, have rarely missed a game and then also won the FA Cup. That's a confidence boost for the World Cup."

Mertesacker will be one of the few Germany players with a guaranteed place in the starting lineup for the first group game against Portugal on June 16.

"At my age, you need to carefully watch your body, but I have been doing that for years," he added. "I put in a lot of individual work and I have the support of my family.

"But the Bundestrainer [Joachim Loew] also knows that it's been a long season for me, and that I have felt it at the end. That's why it's taken care of here [at Germany's training camp in South Tyrol] that you train individually and that the training is directed into the right channels."